refs https://github.com/TryGhost/Team/issues/1253
- Selecting the `image` style opens the file selector right away
- Avoids an extra click to the user
- Moved `GhFileInput` so that it's always rendered, which enables triggering it right when selecting the `image` style
refs https://github.com/TryGhost/Team/issues/1253
- added the card width back (only regular or full options)
- removed the accent class from the button
- fixed a bug happening when the subheader was empty